Which plywood does the designer specify?

[jacquesmm]

In the coming weeks, I will revise what I wrote over the years in study plans and HowTo files about plywood selection.
Some of my comments date from 12 years ago and the situation changed.
The type of boat plans we sell changed and the quality of the plywood changed. Until now, I did not find the time to change my comments and that provokes some confusion. Let's make things clear,

12 years ago, we sold exclusively plans for small boats. No planing boats, no boats that stayed in the water, only dinghies. For those boats, almost any wood will do as long as it has no voids and an exterior glue.
Excellent quality exterior Lauan 1/4" was available for $ 12.00 a sheet!
My statement that " almost any plywood will do because it's the epoxy that counts" apllies to those boats, not to others.
When we started to show plans for offshore boats like the VG20 and planing boats, we began to specify marine plywood in particular Marine Tech.
For mechanical reasons, those boats require a better core, a better plywood.
MarineTech was a fir marine plywood. It was cheap but it checks.
Over the years, the price of marine fir went up and the quality went down. We switched to Meranti and Okoume, BS1088 or BS6566.
Meranti BS6566 was a great choice: cost less than marine fir, stronger and doesn't check.
We had a great supply of BS6566 but it did not last and what we see since two years is so bad that we refuse to ship it.
We are left with BS1088.
Today, for our planing boats and offshore boats, the only type of plywood we recommend is Meranti or Okoume BS1088.
Small boats can still be made of almost any type of plywood but good Lauan is gone and what we see on the shelves is junk that will not last. Even for small boats, I would use BS1088.

[jacquesmm]

Update, July 2007.

The previous post is 2 years old and the plywood situation has improved.
We now stock large quantities of marine plywood and have more control over the quality.

This applies to the Meranti BS6566 from BoatBuilderCentral, not to all types of BS6566. We have seen some very poor quality Meranti and Okoume made in China. We do not stock that type of plywood.

The Meranti BS6566 that BoatBuilderCentral stock today is really good and perfectly suitable for all interior parts and in some cases for the outside skin of the hull:
http://plywood.e-boat.net/products.php?id=6

It is always superior to marine fir: less voids, more plies, better wood, no checking and the price is the same or less than what you will pay for fir marine at an home improvement store.

[kcjonz]

I am building a Cat Ketch 17. you are currently out of Meranti in 1/2" is it OK to use Okume for the bottom and dagger board/rudder and Meranti on the rest of the boat?

Paul

[kcjonz]

I went to Home Depot yesterday. They have several choices for 1x2s

pine is the cheapest, fir is more but not very clear or straight

Poplar is very clear with no knots. would it be OK? it is the most expensive but I'm not sure how well it will soak up the epoxy. Does it matter if the cleats are very good wood?

Paul

[gk108]

Pine and fir are OK. Avoid using poplar and red oak for anything on a boat.

[BassinVt]

My question is this. I can get meranti or okoume in my area. Roughly $125.00 a sheet. Or i can get marine fir for $35.00 a sheet. My build,hoping to start in the next couple weeks will be the GL16 garvey/jon boat. No real *bending* of wood to be concerned about. Everything Ive read on here about inferior grades causing checking, and inferior grades not having the voids filled properly.. With this style of build, and its going to have fiberglass over it, wouldnt the Fir marine grade work fine?? My reasoning is this, its a small boat, no real horsepower is going to be on. A garvey or john boat up here in vermont, really is just used for local ponds and small lakes. So it wouldnt take a real pounding like it would in large lakes. So with the addition of fiberglass matting, and resin wouldnt it be strong enough with the marine fir? Or is marine fir really only designed for say interior components say like on a sailboat? Thanks for your reply and keep up the great forum.

[tech_support]

yes, marine grad fir will work. You should cover it in a light woven cloth to prevent checking.

[jacquesmm]

Please start a new thread, this one is 5 years old.
I lock this one.
BTW, right now, our supply of BS6566 is great.
Plywood supply changes, what we said 15 years ago does not apply today.